Two avian reoviruses, strain Reo-25 and isolate W3-492 were given by mouth to eight one-day-old chicks. 3-7 days after inoculation, the liver, spleen, pancreas, caecal tonsil and duodenum were collected, weighed and titrated in cell culture for viral content. Tissue homogenates were passaged several times in day-old chicks. Reo-25 virus was passaged at 3-day and W3-492 virus at 3- and 7- or 14-day intervals. For both Reo-25 and W3-492 viruses, pathological effects and virus yields in tissues Show moreTwo avian reoviruses, strain Reo-25 and isolate W3-492 were given by mouth to eight one-day-old chicks. 3-7 days after inoculation, the liver, spleen, pancreas, caecal tonsil and duodenum were collected, weighed and titrated in cell culture for viral content. Tissue homogenates were passaged several times in day-old chicks. Reo-25 virus was passaged at 3-day and W3-492 virus at 3- and 7- or 14-day intervals. For both Reo-25 and W3-492 viruses, pathological effects and virus yields in tissues decreased with continued passages. In direct comparisons of reovirus W3-492 before chick passage (PO) and after four passages at 7-day intervals (P4) using standardised amounts of virus for inoculation of chickens, no major differences in pathological effects were observed. P4 virus could be recovered from duodenal tissue at 28 days and from liver tissue at 14 days. PO virus could be recovered from duodenal tissue at 14 days and from liver tissue at 10 days.. Show less